Friday, July 19, 2013

Vitamin D during breastfeeding

Dr Bruce Hollis, Professor of Pediatrics, College of Medicine, Medical University of South Carolina has been researching vitamin D in pregnancy and breastfeeding since 1978. One of his research partners is Dr. Carol Wagner.

Hollis debunks “the well known fact that human milk is a poor source of vitamin D for the nursing infant.” He says this is an absolutely false and absurd statement. But the belief can be traced back to the Institute of Medicine recommendations. If a woman is only receiving 400IU/day, then her milk is indeed a poor source. 

Once, cutaneous generation of vitamin D was all we needed. In Africa, our black-skinned ancestors ran around with no clothes, enjoying unlimited sunlight, making all the vitamin D we needed. However, when we got to N Europe we all turned into pale-skinned individuals, a genetic adaptation to cope with less sunlight exposure. This pigmentation loss happened about 12,000 years ago. 

A single initial MED dose of UVB radiation to a light-skinned individual will release 20,000 IU vitamin D (total body exposure for 20 minutes). However, dark-skinned individuals need 10-fold exposure, which creates a problem for those individuals at high latitudes. For example, there is a very high incidence of rickets in breastfed babies of dark-skinned mothers.

Vitamin D was once considered a teratogen!?! Hollis responds to the question ... “How toxic is vitamin D?” Upper dose was originally set  at 2,000IU/day. But when you can make 20,000 IU from 20 min in the sun, this is clearly ridiculous. New level is set at 4,000 IU day, which is still arbitrary but just better than 2,000 IU. Hollis also comments on the statement “Breastfed infants are at especially high risk of D deficiency due to poor penetrance of vitamin D metabolites into milk.” He says it’s not the metabolites that go into milk, it’s the active form 25(OH)D. 400IU/daily is an insignificant amount, with nothing going to the infant. Vitamin D deficiency (in the mother) breeds more deficiency (in the breastfed infant). For every 1,000IU intake by the mother, she provides just 80IU to the breastfed infant. Supplement containing 6,400IU for breastfeeding mother is necessary to get any useful amount of vitamin D into the baby. 

In summary:
No adverse events related to supplementation
Must take every day! 
4,000IU/day during pregnancy
Nursing mothers need at least 6,000IU/day. 
Bottle fed infants do not need supplements. 

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